Other Assets - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Venture Capital Investments [Member]
Other Assets Non Current [Line Items]
Venture capital investment, business acquisitions	$ 12,021,000	$ 9,125,000
Minimum [Member]
Other Assets Non Current [Line Items]
Percentage of interest acquired	2.00%	4.70%
Maximum [Member]
Other Assets Non Current [Line Items]
Percentage of interest acquired	8.30%	19.70%